Here is the proven reliable CoastalRat way to determine if someone likes you. Please follow these steps carefully or it will not work.
Step 1 - Walk up to your crush.
Step 2 - Stand in front of him.
Step 3 - Look him or her in the eyes.
Step 4 - Lean forward and plant a kiss on his/her lips.
Step 5 - Tell him/her you've wanted to do that for a long time.
Now, if your crush runs screaming from your presence, then he/she probably is not interested and you may have to face disciplinary action if this happens at school or the work place. If he/she looks back at you and says "Wow, I always wanted to do that to you" then you know he is interested.
Let me know how it goes and remember, I am always interested in attending wedding receptions with an open bar. You can thank me then.